As shown in FIG. 1, a conventional high chair 9′ (or a stroller) mainly comprises a seat portion 1′, a backrest 2′, an arm 12′, a frame 4′ and a plurality of wheels 8′, all of which are pivotally connected as well as a tray 3′ being connected to the arm 12′. However, when the conventional high chair 9′ is collapsed, only the inverse V-shaped frame 4′ is collapsible into two parallel bars or the backrest 2′ is adjustable to parallel with the frame 4′. However the angle between the seat portion 1′ and the frame 4′ can by no means be adjusted. Therefore, the front-rear seat portion 1′, which is almost perpendicular to the frame 4′, has a large longitudinal size. This not only results in lots of packing material being consumed but also too much transportation space being occupied, which increases the packing material and the transportation cost and moreover is inconvenient for users to carry outdoors.
On the other hand, the conventional high chair 9′ only has a button (not shown) for collapsing the high chair 9′. Hence, if the button is mistakenly pressed or broken down, the infant in the high chair 9′ may drop down or be jammed.